This is why you shouldn’t go to extremes to lose weight

If you want to lose weight and look good in those trunks this summer, rethink that extreme diet plan. Drastically cutting your calories to slim down has long-term effects on your health, revealed preliminary research presented at a recent European Congress on Obesity.

People who ate an extremely low-calorie diet (500 calories a day) for five weeks lost a similar amount of weight as those on another restricted low-calorie diet (1,250 calories a day) for 12 weeks—19 and 18 pounds, respectively. But it was the starvation diet group that lost more muscle, and even a month after stopping the diet they had significantly less lean muscle as the other group.

Obviously both diets in the study cut calorie levels to ridiculous levels, particularly for men. Any calorie restriction for weight loss should be more tailored based on your own weight, says Christopher Mohr, Ph.D., RD. So if you're over 200 pounds and want to drop weight, you should aim for no less than 1,800 calories.

Extreme calorie-cutting forces your body to burn muscle for fuel instead of fat, and having less muscle mass slows your metabolism. But the truth is many dieters only care about the number on the scale versus what’s going on inside the body, says Jim White, RD, owner of Jim White Fitness and Nutrition Studios in Virginia Beach. For long-term weight loss, crash diets won’t work—and not only because they reduce your muscle mass. Here are four more reasons to avoid the fast fix:

It’s mostly water: Yeah, you can shed a lot of weight before your buddy’s wedding with an extreme diet that cuts carbs. For every carb gram you consume, your body retains 4 grams of water, explains White. Drop pasta, rice, and other grains from your diet for three days and you’ll pee out a bunch of water and look slimmer. But it’s not fat you’re losing, and it’s all temporary once you eat normal again or drink water.

They hurt your body: Losing weight quickly and then regaining it—yo-yo dieting—is taxing to your cardiovascular system, suggests a study in the International Journal of Obesity. More proof: a 2013 animal study in the journal Diabetes suggests that yo-yoing alters fat tissue and decreases glucose tolerance, which could increase your risk of diabetes and heart disease.

It’s not sustainable: Extreme diets are definitely not about moderation. They have rules to follow and cut out entire food groups, making it impossible to have a social life, says White. (Unless you want to be that guy ordering an undressed salad when everyone else gets pizza.) And research in New England Journal of Medicine showed that those on a very-low-calorie diet for 10 weeks had lower levels of the “fullness” hormones leptin and peptide YY to go along with an increase in the hunger hormone ghrelin. The dieters said their appetites were greater, too—even a year later.

Your friends will nickname you “Misery”: Shocker, being hungry and starved for nutrients will turn you into a grumpy, moody, and tired person. One study in the Journal of Consumer Research found that when people had to use high levels of self-control—like during dieting—they were more likely to prefer angry messages and displayed higher levels of irritability. After all, most of the brain’s energy runs on carbs, says White.

Your plan: If you want weight loss that lasts, drop the extreme diet mentality. (And you can start by checking out our #CountdownToSummer for the best diet advice available.) Watching portions is the best thing you can do to lose weight, says White. Then, think about the little things you can do to cut calories from your day: milk instead of cream and sugar in your coffee, choose a leaner cut of steak, or serve yourself extra vegetables instead of rice.